At 4 min, 25 sec, he sends meat boy to the right wall then simply detaches without jumping to get to the left wall. I don't know how to do that. The whole time I was waiting till the last second, then barely jumping to avoid the razor blades and get to the left wall.

Yeah, if you're on the right wall and you hold left, you'll *eventually* detach from the wall. It does take a bit of time though, you stay stuck to the wall for a bit and once you come off you're only moving left fairly slowly.